Chapter 3

Minerals

MineralNaturally occurring

Inorganic

Solid

Definite structure – crystalline – solid in which the atoms are arranged in a repeating pattern.

Definite compositionEx; Quartz - SiO2

Coal

Naturally occurring

Made of organic material

plants

Solid – non crystalline

Definite composition

Cubic zirconiumMan made

Inorganic material

Solid

Crystalline structure

Definite composition

ice

quartz

Hexagonal Crystal( 6 sides)

Had plenty of time and space to allow the crystal to grow

Same crystal shape

Formed in a tight space so you cannot see the outward appearance of a crystal

Fluorite

Pyrite

Galena

Aggregate – clumps of minerals joined together

Pyrite

Galena

Halite

Calcite- double refraction

Formation of minerals1. Cooling magma – cooling slows particles which cause them to move closer together and form compounds.

- molecules arrange themselves into repeating patterns - type and amt of minerals depend on the composition of the magma - many different minerals form - quicker magma cools, faster crystals form, smaller crystal size/or no apparent crystal

2. Crystal from solution – minerals dissolved in liquids

- when liquid evaporates the mineral is left behind

3. Crystals from supersaturated solution – molecules of the mineral fall out of the solution.

98% of the earth’s crust is made of only 8 elements

Silicates – most common rock forming elements

- minerals that contain O and Si

Mineral Identification

Physical properties – observable properties

Hardness – how easily mineral can be scratched

Talc – soft mineral

-scratch with fingernail - talcum powder

Diamond – hardest of all minerals

- only another diamond can scratch it

- used in special cutting tools

Moh’s Scale of HardnessThe Girls Can Flirt And Other Queer Things Can Do1.       talc2.     gypsum3.     calcite4.     fluorite5.     apatite6.     feldspar (orthoclase)7.     quartz8.     topaz9.     corundum10.  diamond

Luster

How light is reflected from a mineral’s surface

Metallic – shines like metal

Nonmetallic luster

Nonmetallic-

glassy,

dull,

pearly,

Silky

Earthy

Greasy

Color

Can’t be depended upon because some minerals have a variety of colors

Some minerals have the same color

Chalcopyrite – left

Gold nugget - below

Streak

Powdered form of a mineral

Rub the mineral across a piece of unglazed porcelain

Left – hematite

Right - pyrite

Graphite

Streak – black to gray

Hardness – 1

Feels – greasy

Luster – metallic

Opal

No streak

Hardness 5-6

Luster – waxy

Fracture and Cleavage

Cleavage – when a mineral breaks along smooth flat surfaces

Fracture – minerals that break with rough or jagged edges

Conchoidal – circular pattern in break

irregular

Other Properties

Magnetic

Double images

Taste – halite/salty

Smell – sulfur – smells like rotten eggs

Reaction to HCl – bubbles.

Fluoresence'